Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2018

Investments, All Other Investments [Abstract]

Schedule of Fair Value on Recurring and Non-recurring Basis

The following table presents information about assets that were recorded at fair value on a recurring and non-recurring basis as of June 30, 2018 and December 31, 2017 and indicate the fair value hierarchy.

	June 30, 2018
(thousands of dollars)	Level 1		Level 2		Level 3		Total
Current Assets
Short-term available-for-sale investments	$	579	$	-	$	-	$	579
Total current assets recorded at fair value	$	579	$	-	$	-	$	579
Non-current Assets
Restricted cash	$	3,668	$	-		-	$	3,668
Total non-current assets recorded at fair value	$	3,668	$	-	$	-	$	3,668
	December 31, 2017
(thousands of dollars)	Level 1		Level 2		Level 3		Total
Current Assets
Short-term available-for-sale investments	$	1,361	$	-	$	-	$	1,361
Total current assets recorded at fair value	$	1,361	$	-	$	-	$	1,361
Non-current Assets
Restricted cash	$	3,668	$	-		-	$	3,668
Total non-current assets recorded at fair value	$	3,668	$	-	$	-	$	3,668